Releasing tool for multiple contact

ABSTRACT

A tool for releasing an electrical contact of a connector assembly including a contact body having a crimped wire barrel portion and a channel portion with a finger-like spring mounted on the channel portion. An opening near a free end of the spring is located opposite one end of the channel permitting insertion of a conductive post through the opening and into the channel. The spring is appropriately biased to bite the post along one edge of the opening while releasing the post by use of a tool which applies a force at the end of the spring in the direction of the channel.

United States Patent [191 Kinkaid et al. v

RELEASING TOOL FOR MULTIPLE CONTACT Inventors: Robert John Kinkaid, New

Cumberland; John Carl Asick, Harrisburg, both of Pa.

Assignee: AMP Incorporated, Harrisburg, Pa. Filed: Sept. 5, 1972 Appl.No.: 285,983

Related US. Application Data Division of Ser. No. 92,742, Nov. 25, 1970,Pat. No. 3,705,376.

US. Cl. 29/203 H Int. Cl B25b 27/02 Field of Search 29/203 H, 206 R, 203HC,

[451 June 25, 1974 3,377,689 4/1968 Kimmett... 29/203 H 3,600,784 8/1971Propst 29/203 H Primary Examiner-Thomas H. Eager Attorney, Agent, orFirm--Gera1d K. Kita [57] ABSTRACT A tool for releasing an electricalcontact of a connector assembly including a contact body having acrimped wire barrel portion and a channel portion with a finger-likespring mounted on the channel portion. An opening near a free end of thespring is located opposite one end of the channel permitting insertionof a conductive post through the opening and into the channel, Thespring is appropriately biased to bite the post along one edge of theopening while releasing the post by use of a tool which applies a forceat the end of the spring in the direction of the channel.

3 Claims, 10 Drawing Figures PATENTEDJUN25I974 3.818.569

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9 I T lNElO saaalsacl-Ellsla HHPLVHEIdIWBL This is a division ofapplication Ser. No. 92,742, filed Nov. 25, 1970 and now U.S. Pat. No.3,705,376.

BACKGROUND OF THE INVENTION This invention relates to connectors and,more particularly, to connectors of the spring contact type forreleasably receiving conductive posts.

Various connectors of the spring contact type have been proposed, butmany spring contacts will not readily release a mating conductive post.In many instances, the connector must be destroyed to break theelectrical connection. In other instances, rather complicated tools mustbe employed to break the connection.

The nature of the electrical contact between the connector and theconductive post is also a source of some difficulty in the springcontact prior art.- For example, the spring contact disclosed in U.S.Pat. No. 1,240,186 Fahnestock does not provide an elongated conductivechannel to assure substantial contact with a conductive post.Furthennore, the spring contact of Fahnestock is examplary of prior artwhich is characterized by an undesirable increase in resistance withtemperature.

In certain cases, the prior art spring contacts have precluded thestacking of contacts on a single conductive post. The spring contactdisclosed in U.S. Pat. No. 2,617,844 Sanda is illustrative.

SUMMARY OF THE INVENTION In accordance with one important aspect of theinvention, a tool for releasing a contact connector of the springcontact type is provided which will readily release the contact from aconductive post. Accordingly, the spring contact comprises a conductivechannel adapted to receive a conductive post and further comprises aspring having an opening located at the end of the channel. The springis appropriately biased to a position characterized by misalignmentbetween an edge of the opening and one side of the channel so as to biteone side of the conductive post at the edge of the opening uponinsertion of the post into the channel through the opening. By applyinga force at the end of the spring adjacent the opening, the conductivepost is released by the spring.

In accordance with another important aspect of the invention, propercontact is made between the channel and the conductive post. In thisconnection, the spring of the connector comprises a fixed portionextending along the channel and a flexible portion including the openingnear the spring end which is free to move about a fulcrum at the end ofthe channel. Upon insertion of the conductive post into the channelthrough the opening in the spring, contact is made between the post andthe channel at the side of the channel opposite the edge of the openingand adjacent the fulcrum of the spring. Another area of contact betweenthe channel and the post is located at the other end of the channel andon the side of the post which the edge of the opening bites.

In accordance with a further important aspect, a tool is provided forthe release of a conductive post from the connector. Such a tool maycomprise hook means for engaging the free end of the spring and anactuated member for applying an axially compressive force on theconnector. As an axially compressive force is applied to the connector,the free end of the spring pivots about the fulcrum forcing the end ofthe spring away from the conductive post to release the bite.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded view of aconnector embodying the invention;

FIG. 2 is a perspective view of the connector shown in FIG. '1;

FIG. 3 is a side view of the connector shown in FIG. 2 in combinationwith a conductive post, the contact being shown in partialcross-section;

FIG. 4 is a side view'of a pair of the connectors shown in FIG. 2stacked on the conductive posts;

FIG. 5 is a perspective view of a tool releasing a conductive post fromthe spring contact of FIG. 2;

FIGS. 6 and 7 depict sequential steps in the operation of the tool shownin FIG. 5;

FIG. 8 is a side view of a pair of modified connectors embodying theinvention which are stacked on a conductive post;

FIG. 9 is a sectional view of one of the connectors shown in FIG. 8; and

FIG. 10 is a graph depicting connector characteristics as a function ofcurrent.

BRIEF DESCRIPTION OF PREFERRED EMBODIMENTS FIG. 1 is an exploded view ofa connector of the spring contact type comprising a body 10 and spring11. As shown, the body includes a channel portion 12 for receiving aconductive post, a transition portion 14, and a wire barrel portion 15axially offset from the channel portion 12 for receiving a wire. Thebody 10 also includes cars 13 which are adapted to bend over a fixedportion 11a of the spring 11.

The spring also includes an arched portion 11b and a locking portionllc. An opening 16 is provided in the locking portion llc which ispartially aligned with the channel when the connector is assembled asshown in FIG. 2. The locking portion 11 of the spring also includes adish 17 which strengthens the spring 11 and, as will be subsequentlyexplained, optimizes the bite of the locking portion llc on the post.

Note that each of the ears 13 is precreased. Therefore, when the earsare bent over the fixed portion of the spring, the resulting bend acrossthe fixed portion llc will be uniform, right-angled and not radiused.This type of bend will not buckle the spring. The wire barrel 15 is bentor crimped over the connecting wire 18 in a substantially conventionalmanner.

FIG. 3 shows the connector in place on a post 19. The arched portion 11bof the spring extends around the corner, or fulcrum point 20 external tothe channel. An edge 21 of the opening 16 is biased to a position ofslight misalignment with one side of the channel before the post 19 isinserted. When the post 19 is inserted into the channel through theopening 16 as shown in FIG. 3, the spring 11 bites, that is, bearsagainst, the post 19 at the edge 21 in the dish 17.

Note that the angle of bite for the spring at the edge 21 is reduced andthereby optimized by the dish 17. Furthermore, the dish 17 formsradiased corners which fit into frictional engagement with the comers ofthe post 19 and improve the holding ability of the connector.

The electrical contact between the post 19 and the channel occurs inthree different areas. One area 22 is adjacent the fulcrum 20. The otherarea 23, is on the opposite side of the channel adjacent the transitionportion 14. The pressure exerted by the spring holding the post 19against the two areas of the channel provides ample electrical contactbetween the post 19 and the channel. There is also electrical contactthrough the spring member.

Referring again to FIG. 3, it will be noted that, when the connector isin place on the post 19, there is a gap 24 between the spring 11 and theportion of the body which forms the channel 12. This gap is importantbecause the spring can be depressed through this gap to release the biteor pressure on the post. Note further that, if the tip of the spring ispushed upwardly or in the direction of the channel portion 12, that is,fulcrumed about the comer 20, the spring pressure is released. In thisembodiment of the invention, it is particularly convenient to applypressure to the wire barrel and to the tip of the spring 11 to increasethe arch in the arched portion 11c and release the pressure on the post19. In this manner there is provided a connector which is truly a zeroforce connector when it is applied. However, after it is applied to thepost 19 and the spring bites, the connector cannot be pulled off. It hasbeen found that the wire 18 will pull out the wire barrel 15 before theconnector will pull off the post.

FIG. 4 shows two connectors on the post 19. In use, it is commonlynecessary to stack two or more connectors'on a post in this manner andthe connector of this invention is a particularly convenient way ofdoing so.

FIG. 5 shows a tool for releasing the spring. The tool includes achannel portion which receives the connector and post and books 26 whichhold the end of the spring 11. A spring-loaded plunger 27 is movedtoward the hook by hand operation of the handle 28 thereby applying anaxially compressive component of force on the connector as a force isapplied to the free end of the spring 11 directed toward the channel 12.FIG. 6 shows the plunger 27 in the position before pressure is appliedby the operator. FIG. 7 shows that the hooks 26 which extendperpendicular to the axis of the channel 12 and plunger 27 have beenmovedcloser to each other to further arch the edge 21 of spring 11 awayfrom the post 19 thereby further pivoting the spring around the fulcrum20 to release the pressure between the post 19 and the body 10. Theactual movement of the plunger 27 is very slight as is apparent from aninspection of FIGS. 6 and 7 but is sufiicient for releasing the springfrom the post.

One particularly useful modification of the tool has an overcenter leverwhich pushes the plunger 27 forward. With this modification the operatorneed not maintain the pressure on the plunger 27 while pulling theconnector from the post 19.

FIGS. 8 and 9 show a modified connector embodying the invention. In thismodification the wire barrel 15 is on the same side as the fixed springportion 110. A hole 29 has also been provided in the transition portion.The post extends through this hole. This modification is particularlyuseful where the connectors are applied by an automated machine. Notethat it is not necessary to reverse or rotate two adjacent, stackedconnectors by 180 with respect to one another. In this modification ofthe invention, an ear 30 is provided for exerting pressure to releasethe spring 11. If pressure were applied between the tip of the spring 11and the wire barrel 15, as in the embodiment of FIG. 2, the spring wouldkink. This is avoided by applying pressure between the car 30 and thetip of the spring 11 to release the bite on the post 19.

FIG. 9 shows the spring 11 in its relaxed position before the post isinserted for the first time. Note the misalignment between the edge 21and the side of the channel 12. After the post 19 is inserted into thechannel 12 through the opening 16, the spring 11 will be bent to aposition shown in FIG. 8 while the memory of the spring holds the edge21 against the post 19.

' In one actual embodiment of the invention, the' spring 1 1comprisedstainless steel having a modulus of elasticity of 28 X 10 lbs.The body comprised phosphor bronze although other materials are suitablefor use. Other suitable materials include soft copper, grade C copper orany other good conductive material. In one embodiment, the connector ofFIGS. 1-4 comprises a body in which the channel portion 12 has a squarecross-section 0.028 i- 0.001 inches on a side. The square cross-sectionof the post 19 is 0.025 t 0.001 inches on a side. In the modification ofFIGS. 8 and 9, one actual embodiment has a channel 12 with a rectangularcross-section, 0.034 t 0.002 by 0.067 t 0.002. The post in thisembodiment is 0.031 t 0.001 by 0.062 0.001 inches.

The connector of the present invention exhibits a re- 'sistance versuscurrent characteristic. Normally, as the current through a connectorincreases, the resistance increases. This causes the temperature toincrease and the voltage drop across the connector to increase.

However, the connectorofthe present invention exhibits a negativeresistance characteristic. As heat is generated in the connector byincreased current, the body 10 expands faster than the spring 11 due tothe different coefficient of expansion between spring and body. In theembodiment previously described, the coefficient of expansion ofstainless steel is lessthan that of a phosphor bronze body. Asthe body10 expands, the fulcrum point or corner 20 engages the spring 11 withincreased pressure to increase the bias on the spring 11. The increasedbias on the spring improves the contact between the post 19 and the body10.

This characteristic is demonstrated by the graph of FIG. 10 whichcontains two plots. The first is a plot of termination resistance inmilliohms as a function of current. The Xs are average values of testson five samples. The bars above and below the Xs represent the maximumand minimum resistance exhibited for each of the five samples. Note thatas the current increased from 0.5 amps to 3.5 amps; there was a decreasein average termination resistance from 1.00 to 0.95 milliohms. This isabout 6 percent decrease in resistance.

The other plot in FIG. 10 is a plot of temperature as a function ofcurrent. The temperature indicated on the ordinate is the differencebetween ambient temperature and the temperature of the transitionportion 14 of the connector. This is usually considered a hot spot inconnectors. Note that there is approximately a 10 increase intemperature. This represents approximately a 50 percent rise intemperature while the contact actually exhibited a 6 percent decrease inresistance. The foregoing test demonstrates that within the parametersof the connector design there is a decreasing resistance instead of thenormal increasing resistance with increased current.

Various modifications of the disclosed embodiments of the invention maybe made without departing from the scope of the appended claims.

What is claimed is:

1. A tool for use in releasing a conductive post from a connector of thetype comprising a conductive channel portion adapted to receive the postand a spring having an end fixed with respect to said channel and a freeend having an opening located at one end of the channel, the free end ofthe spring being biased about a fulcrum so as to bite the post with anedge of the opening and lock the post in place, said tool comprismg:

a connector receiving section including means for engaging saidconnector at the extremity of said free 6 end;

a depressible plunger cooperating with said connector receiving sectionfor engaging said connector nearer said fixed end of said spring thansaid free end, said plunger applying a substantially axially compressivecomponent of force along said channel so as to pivot said free end ofsaid spring about said fulcrum thereby releasing the bite on said post.

located in said channel of said tool.

1. A tool for use in releasing a conductive post from a connector of thetype comprising a conductive channel portion adapted to receive the postand a spring having an end fixed with respect to said channel and a freeend having an opening located at one end of the channel, the free end ofthe spring being biased about a fulcrum so as to bite the post with anedge of the opening and lock the post in place, said tool comprising: aconnector receiving section including means for engaging said connectorat the extremity of said free end; a depressible plunger cooperatingwith said connector receiving section for engaging said connector nearersaid fixed end of said spring than said free end, said plunger applyinga substantially axially compressive component of force along saidchannel so as to pivot said free end of said spring about said fulcrumthereby releasing the bite on said post.
 2. The tool of claim 1 whereinsaid connector receiving section forms a channel for receiving saidconNector.
 3. The tool of claim 2 wherein said means for engaging saidspring comprises at least one hook projecting substantiallyperpendicular to the axis of a connector located in said channel of saidtool.